问题
选择题
Mary __________ the job he offered to her, but she didn’t.
A．can’t take
B．ought to have taken
C．should take
D．must have taken
答案
答案：B
考查虚拟语气。Ought to have taken="should" have taken意为：本应该做却未做；
根据后面的but she didn’t可知这是一个与过去事实相反的虚拟语气。
应该用：情态动词+have done的形式。